System and method for processing audio signals

ABSTRACT

A system for processing audio signals is disclosed. The system comprises a computer with a digital audio workstation (DAW) software installed, an audio interface coupled to or integrated with the computer, an analog audio processor (AAP) hardware coupled to the audio interface. A digital audio stream from within the DAW software is converted, via the audio interface, to an analog audio signal, then routed through the AAP hardware for fully analog processing and altering, then converted back, via the audio interface, to an altered digital audio stream and finally routed back to the DAW software. The DAW software comprises an AAP plugin which controls a number of audio processing settings of the AAP hardware via a control connection between the AAP plugin and the AAP hardware. The AAP plugin comprises a digital signal processor (DSP) subroutine which applies digital audio effects on the previously altered digital audio stream.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to European Pat. App. No. 22166126.7,filed Mar. 31, 2022 and also titled “System and method for processingaudio signals”, which is hereby incorporated by reference in itsentirety.

FIELD OF INVENTION

The invention relates to a system for processing audio signals orstreams. It also relates to a corresponding method.

BACKGROUND

Published European patent application EP 3 537 632 A1 recognizes thatmany audio engineers prefer using analog devices that work with analogsignals over digital devices, believing that analog devices have betteracoustic characteristics. However, a disadvantage with analog devices isthat the user typically relies on memory each time new parametersettings are made. It is also difficult to store parameter changes as afunction of time, and changing these values as a function of timeinvolves dedicated personnel to mechanically change settings.

To this end said application discloses an analog device control system.The analog device control system has an analog device control module,comprising computer-executable code stored in non-volatile memory, aprocessor, and an analog device. The analog device control module, theprocessor, and the analog device are configured to use the analog deviceto receive an analog signal, digitally control the analog device usingthe analog device control module, and vary the analog signal using theanalog device. Varying the analog signal is based on digitallycontrolling the analog device using the analog device control module.

BRIEF SUMMARY

One objective underlying the present invention is to further increaseusability and functionality of said prior art system, while furthermaintaining audio quality, keeping the analog device simple, and makingefficient use of hardware resources.

According to the invention, the objective is achieved by a systemaccording to claim 1. A corresponding method is specified in claim 10.

Therefore, according to the invention, a system for processing audiosignals is disclosed, the system comprising a computer with a digitalaudio workstation (DAW) software installed (i.e. the computer togetherwith the software realizes a DAW), an audio interface coupled to orintegrated with the computer, an analog audio processor (AAP) hardwarecoupled to the audio interface, such that a digital audio stream fromwithin the DAW software can be converted, via the audio interface, to ananalog audio signal, then routed through the AAP hardware for fullyanalog processing and altering, then converted back, via the audiointerface, to an altered digital audio stream and finally routed back tothe DAW software, wherein the DAW software comprises an AAP plugin whichcontrols a number of audio processing settings of the AAP hardware via acontrol connection between the AAP plugin and the AAP hardware, andwherein the AAP plugin comprises a digital signal processor (DSP)subroutine which is capable of applying digital audio effects on thepreviously altered digital audio stream, thereby further altering itdigitally.

The invention is based on the idea of providing digital recall for anAAP hardware via a digital control plugin in an extended DAWenvironment, and at the same time adding to the plugin DSP functionalitythat actually additionally alters the audio signal despite thepredominant analog processing before. Hence, on a conceptional levelthere is hybrid audio signal manipulation combining analog processingand DSP processing in one elegant, effective, and reliable system ofhighest audiophile quality. The plugin therefore has at least twopurposes: firstly, controlling the analog hardware, secondly processingthe digital signal in the DAW, and optionally analyzing the signal inthe DAW, in particular with respect to DSP operations unrelated toanalog processing.

This concept has a number of unexpected advantages:

The extended control plugin (i.e. the AAP plugin, also named DSP pluginwhen referring to the DSP functionality only) receives control andmetering signals from both the analog hardware (i.e. the AAP hardware)and the DSP process, so that one can monitor and adjust both processes(that are in fact influencing each other) at the same time.

The user can narrow down the amount of space taken up on the screen of agraphical user interface to make audio signal manipulations.

The plugin also can double as a standalone DSP plugin without the needof using the analog hardware.

This integration improves a lot the creative process as the operator isconcentrated only on one interface and not distracted by multipleinstances of the processors needed elsewhere for audio editing.

The audio DSP process is very CPU consuming, so it is advantageous tounload some processes from the analog hardware to the DAW which isnaturally equipped for CPU-intense processes, such as: signal detection,audio analysis for sidechain, FFT analysis, or machine learning.Therefore, it is no longer necessary to use heavy chips and complicatedprogramming in the analog hardware, while at the same time lessresource-intense audio processing like raw analog signal processing canbe kept at the analog device (i.e. the AAP) for highest audiophileresults.

Nowadays, most of music or similar audio content is published asdigital, in particular via the internet (e.g. via streaming services).However, the AAP devices are analog ones on purpose. Because of thatthere may be some differences between analog metering and digital one.The solution described herein adds the possibility for a user to havedigital accuracy of measurement or metering of the sound effects appliedinside the analog device that corresponds to a song published digitally.

In a preferred embodiment the AAP plugin comprises a machine learningsubroutine which collects and analyzes data based on user behaviordepending on specific audio signals, and which, after some trainingperiod, offers or suggests or automatically applies settings for the AAPhardware and the DSP subroutine. Additionally, the machine learningsubroutine may also collect and analyze data provided by other plugins,e.g. third-party plugins, which may be called or loaded by the DAW. For,example, in an expanded machine-learning scenario there may bethird-party plugins to be applied alone or in sequence with the AAPplugin, and these third-party plugins may be collecting data, inparticular, on user behavior, for their own uses. Preferably, the AAPplugin comprises suitable interfaces to communicate with the otherplugins and to obtain access to their internal databases. This yieldsthe possibility to use data collected by other plugins inside the AAPplugin for machine learning purposes. The entirety of the collected datamay then be used to control and/or predict and/or automatically applysettings of the AAP hardware—and/or preferably of the AAP plugin (inparticular of its digital subroutine) and/or the other plugins.

Advantageously, the DSP subroutine comprises a high-pass filter.

In a preferred embodiment, the DSP subroutine comprises a digitalspectrum analyzer based on a fast Fourier transform algorithm.

The control connection is preferably established via an USB interface.However, Ethernet, Wi-Fi, Bluetooth or other wireless or cable-basedinterfaces or connections may generally be viable alternatives.

The computer is preferably a workstation, personal computer, a laptop, atablet, a handheld, or a smartphone.

In a preferred embodiment the AAP plugin is configured to provide acontrol window on an associated computer screen, the control windowcomprising an AAP control area for metering and adjusting settings ofthe AAP hardware and a digital control area for metering and adjustingsettings of the DSP subroutine.

Expediently, the AAP plugin further provides an analysis area whichdisplays a graphical spectral analysis of the previously altered digitalaudio stream.

In a preferred extension of the basic idea not only the AAP hardware canbe controlled by the DSP plugin or subroutine but also the operator(user) will be able to control through the physical AAP hardwareinterface (knobs, buttons, switches and/or sliders or similar controlelements) the settings or parameters of the DSP plugin (i.e. the DSPsubroutine of the AAP plugin within the DAW). For example, the user canset via a knob on the AAP hardware the cutoff of a digital high-passfilter or any other function build into the DSP subroutine. Hence,control can preferably happen in both directions of the establishedcontrol connection: virtual control elements on a graphicaluser-interface of the DAW can set parameters of the associated analoghardware (i.e. AAP hardware), and physical control elements of theanalog hardware can set parameters of the digital processing inside theDAW environment.

Furthermore, the invention provides a method for processing audiosignals or streams, using a computer with a digital audio workstation(DAW) software installed, an audio interface coupled to or integratedwith the computer, and an analog audio processor (AAP) hardware coupledto the audio interface, wherein a digital audio stream from within theDAW software is converted, via the audio interface, to an analog audiosignal, then routed through the AAP hardware for fully analog processingand altering, then converted back, via the audio interface, to analtered digital audio stream and finally routed back to the DAWsoftware, wherein the DAW software comprises an AAP plugin whichcontrols a number of audio processing settings of the AAP hardware via acontrol connection between the AAP plugin and the AAP hardware, andwherein the AAP plugin comprises a digital signal processor (DSP)subroutine which applies digital audio effects on the previously altereddigital audio stream, thereby further altering it digitally.

BRIEF DESCRIPTION OF THE DRAWINGS

An exemplary embodiment of the invention is subsequently discussed withreference to the accompanying drawings.

FIG. 1 shows a highly simplified schematic of a system for processingaudio signals according to the invention.

FIG. 2 shows a more detailed schematic of said system.

FIG. 3 shows a screenshot of a graphical user interface for adjustingvarious settings of said system.

DETAILED DESCRIPTION OF THE DRAWINGS

The system described herein is an extension of the one described in EP 3537 632 A1, which document is hereby incorporated in its entirety.

FIGS. 1 and 2 provide a schematic overview of a system 2 for processingaudio signals. The system 2 comprises a computer 4 which may be aworkstation, a personal computer (PC), a laptop, a tablet, a smartphone,or any other suitable device, preferably with a central processing unit(CPU), working storage, permanent storage, suitable input and outputinterfaces and related periphery devices, such as a build-in or externalmonitor or screen. The operation of the computer 4 is governed by anoperating system software which allows for loading an executingapplication software 6, in particular a software bundle known as digitalaudio workstation (DAW) software for processing digital audio streams.DAW may also be the denomination of the computer 4 combined with theaudio software. The system further comprises an audio interface 8, alsoknown as sound board or sound card or analog-digital/digital-analog(AD/DA) converter for converting analog audio signals to digital audiostreams and vice versa. While the audio interface 8 may be integral withthe computer 4, it is preferably provided as an external device. Thecomputer 4 and the audio interface 8 are preferably to be coupled via auniversal serial bus (USB) interface with the help of suitableconnectors. The audio interface 8 has a number of audio input ports foranalog audio sources, such like a microphone or an instrument or anauxiliary (AUX) audio line. The audio interface 8 further comprises anumber of audio output ports for corresponding audio output devices,such as audio speakers, studio monitors, or headphones. The may be morethan one audio interface 8 of the kind described above.

During operation of the system 2, an analog audio signal (e.g. from aninstrument or microphone) is converted into a digital audio stream bythe audio interface 8 and is processed by the DAW software on thecomputer 4 (e.g. PC). The DAW has some build-in functionality which canbe extended by third-party audio effect plugins, i.e. software moduleswhich can be called or loaded by the main program. Each plugin, incombination with the computer hardware, acts as a digital signalprocessor (DSP). The DAW can therefore load a number of digital pluginsfor processing the digital audio stream. In particular, a number of DSPplugins may provide well-known audio effects like equalizer (EQ),compressor, reverb, and the like. The effects associated with theindividual plugins are applied sequentially, in any suitable orderchosen by the user as allowed by the application software 6. Theoriginal and the changed versions of the digital audio stream can besaved as digital audio files on the computer. Several tracks can beworked-on or processed simultaneously and mixed according to the user'swishes. For replay, the respective digital audio stream is sent back viathe audio interface 8 to suitable speakers (e.g. studio monitors) orheadphones.

The basic audio system described so far may be extended by a specialanalog audio processor (AAP) hardware 10. This is an analog device orhardware which acts upon an analog audio signal, i.e. provides fullyanalog audio processing. The AAP hardware 10 advantageously is aseparate device. It comprises an audio input port which according toFIG. 2 is connected to an audio output port of the audio interface 8.Similarly, the AAP hardware 10 comprises an audio output port which isconnected to an audio input port of the audio interface 8. This way, adigital audio stream from within the DAW can be converted into an analogaudio signal by the audio interface 8, then routed through the AAPhardware 10, analogously processed therein, and finally converted backinto a digital audio stream via the audio interface 8. The correspondingaudio loop through the AAP hardware 10 which originates and terminatesat an input-output (10) plugin 12 of the DAW software is indicatedschematically in the left half of FIG. 2 . Digital audio streams areindicated by single arrows, analog audio signals are indicated by doublearrows. The 10 plugin 12 used to address the AAP hardware 10 may bebuild-in functionality of the DAW software or may be provided as athird-party plugin.

Thus, a digitally recorded audio stream within the DAW may be sent,after conversion to an analog audio signal, to the AAP hardware 10 forfully analog audio processing with superior processing characteristics.This may include well-known audio effects like EQ, passive filters, andthe like. After analog processing and back-conversion to the digitalregime, the thus-manipulated digital audio stream may be furtherprocessed by the DAW software. This includes digital processing bycorresponding DSP plugins, to be applied in a sequential manner.

Usually, the AAP hardware 10 has its own physical (hardware)settings-interface with corresponding control knobs, sliders, switches,control lights, and the like for adjusting settings of the analog audioprocessing in this device. In order to provide a more convenient userinterface and also to allow for recall and/or automation of settings,there is a control connection 14, established for example via a USBinterface, between the AAP hardware 10 and a corresponding controlplugin within the DAW. The control plugin preferably provides, amongothers, a virtual replica of the physical AAP settings interface plusassociated automation tools for digital recall and automation of AAPsettings. A corresponding (bi-directional) communication or controlchannel is indicated in FIG. 2 by the dashed arrow. A suitable AD/DAinterface for the control connection 14 may conveniently be integratedinto the AAP hardware 10.

In a basic system design, the control plugin merely controls the AAPhardware 10 but does not act on the digital audio stream, i.e. does notoperate as a DSP. However, according to the invention, a new AAP plugin16 to be called by the DAW software acts as a combined control anddigital effects plugin, therefore providing hybrid (digital plus analog)audio manipulation. That is, the AAP plugin 16 does not merely controlthe settings of the AAP hardware 10 but also applies digital effects onthe digital audio stream generated from the AAP hardware's 10 output.

As explained previously, a digital audio stream processed by the DAW isrouted by the IO plugin 12 via the audio interface 8 through to the AAPhardware 10 for analog audio processing. Afterwards, the thus-processedaudio signal is lead back via the audio interface 8 and the IO plugin 12as a digital audio stream into the DAW software. The digital audio steamis then processed, i.e. generally digitally altered, by the AAP plugin16 which preferably incudes a DSP subroutine 18 or submodule withsuitable digital audio effects. By way of example, the DSP operationprovided by said subroutine, may comprise a high-pass filter. Ifnecessary or desired, the thus-processed digital audio stream mayafterwards be processed by a number of separate third-party plugins insequential plugin stack of the DAW. But this last step is purelyoptional and is preferably not required since the AAP plugin 16 itselfmay provide the necessary digital effects to be applied.

Furthermore, the AAP plugin 16 may provide digital analysis of saiddigital audio stream. For example, it may comprise a digital fastFourier transform (FFT) subroutine for spectral analysis of of the audiosignal represented by the digital audio stream. The analysis may beapplied to the input digital audio stream entering the AAP plugin 16,that is before application of the DSP effects. Alternatively oradditionally, the analysis may be applied after application of the DSPeffects, that is on the output digital audio stream leaving the AAPplugin 16.

As described earlier, the digital AAP plugin 16 also controls the AAPhardware 10 via an associated control connection 14, established forexample via USB, Lightning, or similar interface. More specifically, theAAP plugin 16 facilitates digital recall and automation of audioprocessing settings applied by the AAP hardware 10. That is, with thehelp of a suitable graphical user interface the user can save and loadvarious settings of the AAP plugin 16 which correspond to physicalsettings of the AAP hardware 10. This means, the user does not have toremember a multitude of these hardware settings and turn knobs and setsliders of the AAP hardware 10 accordingly—rather the user can simplyload corresponding settings or preferences in the AAP plugin 16, which,via the established control connection 14, sets the hardware settings ofthe AAP hardware 10 accordingly. These recallable settings preferablyalso comprise digital settings of the DSP subroutine 18 or submodule ofthe AAP plugin 16, e.g. digital filter settings or FFT analyzersettings.

In a preferred embodiment the AAP plugin 16 comprises a machine learningsubmodule or artificial intelligence (AI) submodule. This way, the AAPplugin 16 can and will collect data based on the user behavior dependingon specific audio signals or digital audio streams. It will monitor thedecision-making process based on the incoming signal(s) and in thefuture, after some training phase, offer settings by itself of both AAPhardware 10 settings and DSP settings (in particular digital audioeffects settings) with respect to the DSP subroutine 18 integrated intothe AAP plugin 16.

A schematic screenshot of a control window 20 provided by the AAP plugin16 on a computer screen is shown in FIG. 3 . Basically, the controlwindow 20 is divided into three different areas:

Firstly, the AAP control area 22 comprises a number of digital controlelements for adjusting, loading, and saving settings of the AAP hardware10. This may be a one-to-one, or altered, or digitally enhanced virtualreplica of a physical settings interface of the AAP hardware 10, e.g.with number of virtual EQ control knobs. Alternatively, the AAP hardware10 comprises no physical settings interface on its own or just a reducedversion of it. In any way, AAP control area 22 is the preferred or maininterface for controlling the AAP hardware 10.

Secondly, the digital control 24 area provides control elements foradjusting, loading, and saving settings of the DSP subroutine 18integrated into the AAP plugin 16. By way of example, this includes avirtual switch and control knob for a high-pass filter (HPF).

Thirdly, there is an analysis area 26, by way of example showing agraphical spectrum of the output audio signal at the end of the pluginstack. That is, the graphic representation shows the combined results ofaudio processing in the analog signal chain of the AAP hardware 10 andthe subsequent digital processing in the AAP plugin's 16 own DSPsubroutine 18. In other words, the analysis area 26 graphically depictsthe combined effects of the settings applied both in the AAP controlarea 22 and the digital control area 24. As the hardware and DSP effectsare integrated in to one plugin, AAP plugin 16, one can immediately seeand hear effects of both effects without need to interchange theprocessing plugins.

LIST OF REFERENCE NUMERALS

-   -   2 system    -   4 computer    -   6 software    -   8 audio interface    -   10 AAP hardware    -   12 IO plugin    -   14 control connection    -   16 AAP plugin    -   18 DSP subroutine    -   20 control window    -   22 AAP control area    -   24 digital control area    -   26 analysis area

What is claimed is:
 1. A system for processing audio signals,comprising: a computer with a digital audioworkstation (DAW) softwareinstalled, an audio interface coupled to or integrated with thecomputer, and an analog audio processor (AAP) hardware coupled to theaudio interface, such that a digital audio stream from within the DAWsoftware is converted, via the audio interface, to an analog audiosignal, then routed through the AAP hardware for fully analog processingand altering, then converted back, via the audio interface, to analtered digital audio stream and finally routed back to the DAWsoftware, wherein the DAW software comprises an AAP plugin whichcontrols a number of audio processing settings of the AAP hardware via acontrol connection between the AAP plugin and the AAP hardware, andwherein the AAP plugin comprises a digital signal processor (DSP)subroutine which is capable of applying digital audio effects on thepreviously altered digital audio stream, thereby further altering itdigitally.
 2. The system of claim 1, wherein the AAP plugin comprises amachine learning subroutine which collects and analyzes data based onuser behavior depending on specific audio signals, and which, after sometraining period, offers or suggests or automatically applies settingsfor the AAP hardware and the DSP subroutine.
 3. The system of claim 1,wherein the DSP subroutine comprises a high-pass filter.
 4. The systemof claim 1, wherein the DSP subroutine comprises a digital spectrumanalyzer based on a fast Fourier transform algorithm.
 5. The system ofclaim 1, wherein the control connection is established via an USBinterface.
 6. The system of claim 1, wherein the computer is aworkstation, personal computer, a laptop, a tablet, a handheld, or asmartphone.
 7. The system of claim 1, wherein the AAP plugin isconfigured to provide a control window on an associated computer screen,the control window comprising an AAP control area for metering andadjusting settings of the AAP hardware and a digital control area formetering and adjusting settings of the DSP subroutine.
 8. The system ofclaim 7, wherein the AAP plugin further provides an analysis area whichdisplays a graphical spectral analysis of the previously altered digitalaudio stream.
 9. The system of claim 1, which is configured such thatparameters of the DSP subroutine can be set via a number of physicalcontrol elements of the AAP hardware.
 10. A method for processing audiosignals, using a computer with a digital audio workstation (DAW)software installed, an audio interface coupled to or integrated with thecomputer, and an analog audio processor (AAP) hardware coupled to theaudio interface, wherein a digital audio stream from within the DAWsoftware is converted, via the audio interface, to an analog audiosignal, then routed through the AAP hardware for fully analog processingand altering, then converted back, via the audio interface, to analtered digital audio stream and finally routed back to the DAWsoftware, wherein the DAW software comprises an AAP plugin whichcontrols a number of audio processing settings of the AAP hardware via acontrol connection between the AAP plugin and the AAP hardware, andwherein the AAP plugin comprises a digital signal processor (DSP)subroutine which applies digital audio effects on the previously altereddigital audio stream, thereby further altering it digitally.